1. Field of the Invention.
The present invention relates generally to a hand tool, and more particularly to an adjustable wrench, which can hold a movable jaw when it is moved to a predetermined position.
2. Description of the Related Art
A conventional adjustable wrench comprised a handle having a fixed jaw at an end thereof, a movable jaw slidably provided on the handle having a rack and an adjusting worm pivoted on the handle and engaged with the rack of the movable jaw such that the movable jaw can be moved by turning the adjusting worm.
There must be a clearance of teeth left between the rack of the movable jaw and a helical tooth of the adjusting worm so that the adjusting worm can smoothly drive the movable jaw. But the movable jaw can not stand in a fixed position because of the clearance of teeth since the distance between the movable jaw and the fixed jaw can not be kept constant even though the adjusting worm has not been turned.
FIG. 8 shows a conventional apparatus for an adjustable wrench to secure a movable jaw 78. The adjustable wrench has a hole 74 on a handle 72 and a fastening device 76 provided in the hole 74. The fastening device 76 can be screwed into the hole 74 and press the movable jaw 78 to secure the movable jaw.
FIG. 9 shows a second conventional adjustable wrench having a screw bar 82 driven by a nut 80 to press a movable jaw 84.
FIG. 10 shows a third conventional adjustable wrench having a rectangular slide 86 sliding transversely and against a worm 88 to make the worm 88 can not be turned.
FIG. 11 shows a fourth conventional adjustable wrench having a movable plate 90 with teeth 90 thereon engaged with clutch teeth 96 at a movable jaw 94.
FIG. 12 shows a fifth conventional adjustable wrench having a locking disk 98 to secure an adjusting worm 100.
FIG. 13 shows a sixth conventional adjustable wrench having a control mechanism 102 that moves a worm 104 against a movable jaw 106.
The primary objective of the present invention is to provide an adjustable wrench, which has an apparatus to secure the movable jaw to prevent the movable jaw from trembling when it has moved to any position.
According to the objective of the present invention, an adjustable wrench comprises a handle having a head portion and shank, wherein the head portion has a fixed jaw, a transverse guiding slot and an opening communicated with the guiding slot, a movable jaw having a guiding portion and a rack on the guiding portion, wherein the movable jaw receives the guiding portion in the guiding slot of the handle to be moved toward or away from the fixed jaw, an adjusting worm having a through hole at a center thereof and a helical tooth an outer surface thereof, wherein the adjusting worm is received in the opening and engages the helical tooth with the rack of the movable jaw whereby the adjusting worm is turned to drive the movable jaw to move along the guiding slot, and an adjusting device having at least a part thereof received in the through hole of the adjusting worm whereby the adjusting worm is turned freely relative to the adjusting device. The adjusting device is pivoted on the handle to be turned along a rotation axle and the adjusting worm is turned along a rotation axle and the rotation axle of the adjusting device deviates from the rotation axle of the adjusting worm whereby the adjusting device is turned to move the adjusting worm toward or away from the movable jaw.